Industrial Electronics Chapter 7 [Servo Motors]

If the coils around two adjacent field poles are connected in series, the magnetic polarity at their pole faces will be _____

Opposite

In a variable reluctance motor, if the salient poles are 30 degrees apart and the rotor poles are 45 degrees apart, its step angle is _____ degrees

15

The speed of an AC servo motor is controlled by the _____

Amplitude of the signal supplied to the auxiliary winding

The field strength in which the AC brushless servo motor winding is varied to control the speed or position of the rotor is _____

Auxilary

The speed of a moving coil motor (MCM) is varied by _____

Changing the width of DC pulses applied to the armature

If the sequence in which the stator poles are magnetized moves in a CCW direction, the rotor direction of a VR stepper motor will be _____

Clockwise

The runaway condition is possible with a permanent magnet motor (T/F)

False

The amount of force required to move the rotor away from a stationary position is called ____________________

Holding torque

The _____ the number of poles used in a stepper motor, the better the resolution

Larger

The rotor tooth of a variable-reluctance stepper motor moves into an aligned position with a magnetized stator pole to _____ reluctance

Minimize

In a brushless DC motor (BDCM), the field _____

Rotates

In a BDCM, the _____ is a permanent magnet

Rotor

In a brushless DC motor, the ____________________ (rotor, stator) is a permanent magnet

Rotor

When the rotor aligns itself to stator pole 1, the disk is sensed by detectors ____________________ and ____________________; the remaining detector turns on transistor ____________________ and causes current to flow through stator coil ____________________

S1, S3, Q2, 2

The purpose of ____________________ is to stop the rotor movement

SW2

An AC brushless servo motor uses a _____ rotor

Squirrel-cage

To stop the rotor in an AC brushless servo motor, _____

The output of the auxiliary winding drops to zero

The rotor of the AC brushless servo motor has high-resistance conducting bars _____

To prevent rotation when it is single-phased

BDCMs have low maintenance requirements because they do not have brushes (T/F)

True

The moving coil motor (MCM) uses permanent magnet stators, a wound rotor armature, brushes, and commutator, and it operates on the same principle as a permanent magnet DC motor (T/F)

True

The reason why a wound armature PM motor has linear speed-torque characteristics is because there is no EMF induced into the field poles to cause the field strength to vary (T/F)

True

A small DC motor uses a permanent magnet to develop the field flux. Would the motor reverse direction of rotation if the power supply leads were reversed? ____________________ (yes, no)Would the results be the same if a shunt motor which uses an electromagnet to develop the flux had the power leads reversed? ____________________ (yes, no)

yes, no